Sexing a larva

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Pete Eeles
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Sexing a larva

Post by Pete Eeles »

Hi all,

A known phenomenon with Purple Emperor larvae is that their sex can be determined when in the final instar based on the presence (or absence) of a pair of pale patches on the eighth segment that are the developing testes, indicating a male larva. I think I've just found a photo showing this in the Small White also. Does anyone else have anything similar? Thanks!
Purple Emperor - L5 - 2018-9.jpg
Small White - L5 - 2018-7.jpg
Cheers,

- Pete
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Pete Eeles
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Re: Sexing a larva

Post by Pete Eeles »

Green-veined White too!
Green-Veined White - larva - Thatcham - 04-Oct-11 (1) {REARED}.jpg
Cheers,

- Pete
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Re: Sexing a larva

Post by Vince Massimo »

Hi Pete,
I have seen this as well in both Small White and Green-veined White, but not just in their final instars. I have noted patches of colour (usually purple) showing up on the 8th segment (abdominal segment A5) of some larvae in their 4th instar.

Small White

Male larvae
Small White (4th instar) larva #1
Small White (4th instar) larva #1
Small White (4th instar) larva #2
Small White (4th instar) larva #2
Small White (5th instar) larva #2
Small White (5th instar) larva #2
Small White (5th instar) larva #3
Small White (5th instar) larva #3
Female larva for comparison
Small White (5th instar) larva #4 female
Small White (5th instar) larva #4 female
Small White (5th instar) female pupa #4
Small White (5th instar) female pupa #4
Green-veined White

Male larvae
Green-veined White (4th instar) larva #1
Green-veined White (4th instar) larva #1
Green-veined White (5th instar) larva #1
Green-veined White (5th instar) larva #1
Green-veined White (5th instar) larva #1
Green-veined White (5th instar) larva #1
Green-veined White (pupa) male #1
Green-veined White (pupa) male #1
Green-veined White male #1
Green-veined White male #1
I have also had a quick scan of other species (concentrating on those that have green larvae) and Ben Smart's Small Skipper looked promising although the pale marks appear to be in the 9th segment (A6) rather than the 8th.
Small Skipper (Ben Smart)
Small Skipper (Ben Smart)
Small Skipper (Ben Smart)
Small Skipper (Ben Smart)
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Re: Sexing a larva

Post by Butterflysaurus rex »

Wall Brown? There definitely appears to be a paler mark in the same area as the other larvae shown.
Wall Brown Catterpillar_02.jpg
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Re: Sexing a larva

Post by Pete Eeles »

Thanks Vince and James!

Some interested thoughts from Mark Youles here: http://apaturairis.blogspot.com/2014/02 ... exing.html

Cheers,

- Pete
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Re: Sexing a larva

Post by Pete Eeles »

Going through my archive, I think that this final instar Silver-spotted Skipper may also show its developing testes.
Silver-spotted Skipper - larva - Thatcham - 16-Jul-13 (2) [REARED].jpg
Cheers,

- Pete
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Re: Sexing a larva

Post by MrSp0ck »

is this just for butterflies, or do moths eg Hawk Moth also show this. Although on the hairy larvae it would be very difficult to see. Im not sure if Glanville larvae do either will look later in the season.
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Re: Sexing a larva

Post by Pete Eeles »

MrSp0ck wrote:is this just for butterflies, or do moths eg Hawk Moth also show this. Although on the hairy larvae it would be very difficult to see. Im not sure if Glanville larvae do either will look later in the season.
The phenomenon seems most prevalent in species whose final instar larvae have few (or no) hairs and a pale ground colour, so I suspect it's seen in some moth larvae too, but I don't think you'd see it in a Glanville Fritillary larva for these reasons.

Cheers,

- Pete
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Re: Sexing a larva

Post by Pete Eeles »

I'm currently working on the Large Skipper species description and came across this 2nd instar larva - the first time I've seen anything that might hint at testes in anything other than a final instar larva!
Large Skipper - L2 - Thatcham - 16-Aug-17 [REARED]-2.jpg
Definitely a topic to be studied in more detail at some point!

Cheers,

- Pete

[Edit] Here's a 4th instar, also with the pale markings.
Large Skipper - larva - Pamber Forest - 10-Aug-14.jpg
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Re: Sexing a larva

Post by bugboy »

Some addictions are good for the soul!
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Re: Sexing a larva

Post by MrSp0ck »

We were working on the Emperor Moth larvae, and think the spotting in the last instar may be different sexes too, the pink and the yellow in the black bands, when we do the species again, the larvae will be sorted so adults emerge in different cages, to see if males and females are all in the same cages.

Are the marks on the same segments on the male pupae as the last intar larvae ? We have all been straining our eyes looking at moth pupae all these years looking for the 2 bumps/marks.
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Re: Sexing a larva

Post by Pete Eeles »

MrSp0ck wrote:Are the marks on the same segments on the male pupae as the last intar larvae ?
I don't think so - the testes always 'show' on the 8th segment, whereas the diagnostics for sexing of pupae is based on the position of the genitalia at the end of the abdomen (see http://www.ukleps.org/sexingpupae.html).

Cheers,

- Pete
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Re: Sexing a larva

Post by Pete Eeles »

And another example - Wood White, 4th instar!
sinapis L4.jpg
Cheers,

- Pete
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Re: Sexing a larva

Post by David M »

Fascinating stuff. I trust that this information will be included in your forthcoming work, Pete?
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Re: Sexing a larva

Post by Pete Eeles »

David M wrote:Fascinating stuff. I trust that this information will be included in your forthcoming work, Pete?
Thanks David. It does get a mention in the Purple Emperor description, but will probably become an article post-book!

Cheers,

- Pete
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Re: Sexing a larva

Post by David M »

Thanks for that, Pete. Looks like this publication will help stave off the depression next winter. :)
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